The present invention relates to a variable displacement piston pump motor suited for serving as an oil-pressure source for hydraulic presses and the like.
Japanese laid-open patent publication number 7-118653 describes an example of a variable displacement piston pump/motor that allows the rotational output or the discharge capacity of a pump to be controlled by manipulating the tilting angle (theta) of an input or an output shaft. Japanese laid-open patent publication number 10-18962 describes a swash-plate variable displacement oil-pressure pump that controls a reciprocating axial piston inside a cylinder block by tilting a swash plate forward or back from a neutral position perpendicular to a drive axis using a manually-operated lever.
Japanese laid-open patent publication number 9-42340 discloses a wet clutch/brake device in which an output shaft is kept engaged at all times to a brake plate of a multi-plate brake device. When the output shaft is to be rotated while engaged to a casing, air pressure displaces a cylindrical cylinder toward the output shaft, and rotation takes place via the clutch device with the brake released.
While both Japanese laid-open patent publication number 7-118653 and Japanese laid-open patent publication number 10-18962 allow the pump discharge volume to be changed freely by varying the tiling angle of the swash plate, it is assumed that the pump device will be used by itself and does not consider situations such as when the drive shaft is connected directly to another clutch device. Also, the latter publication is solely a wet clutch/brake device for machine presses, and no consideration is made for directly connecting to a variable displacement piston pump/motor.
The object of the present invention is to provide an energy-conserving variable displacement piston pump/motor with a compact, simple structure that is suited for serving as an oil-pressure generating for machine presses and the like.
Another object of the present invention is to provide an energy-conserving variable displacement piston pump/motor with a compact, simple structure that can be efficiently started and stopped.
According to one aspect, the present invention provides a variable displacement piston pump/motor wherein rotation energy accumulated in a flywheel is transferred via a clutch device to a pump device to provide rotation and generate oil pressure. A drive shaft of the pump device is rotated via the flywheel is disposed and connected concentrically with a driven shaft.
In the present invention, a flywheel is disposed in an overlapping manner concentrically with the pump drive shaft and equipped with a clutch that opens and closes a connection to the pump device and a brake device accelerating the stopping of the pump device. In the present invention, the driven shaft and the drive shaft of the pump device are connected by a coupling.
According to another aspect, the present invention provides a variable displacement piston pump/motor wherein rotation energy accumulated in a flywheel is transferred via a clutch device to a pump device to provide rotation and generate oil pressure. The variable displacement piston pump/motor includes: an electric motor; a cylindrical boss rotatably supporting a drive shaft of a pump rotated by an electric motor and fixed on fixed frames serving as side walls; a hollow flywheel rotatably supported on an outer perimeter of the cylindrical boss, disposed in an overlapping manner concentrically with the cylindrical boss and the pump drive shaft, and rotating integrally with an input shaft rotated by the output from the electric motor; a multiplate clutch device interposed between an inner perimeter end surface of the flywheel and an inner perimeter end surface of pump drive shaft; a multi-plate brake device disposed parallel to the multi-plate clutch device and interposed between the outer perimeter of the pump drive shaft and a fixed support plate formed integrally with the cylindrical boss; a driven shaft connected with a coupling to the pump drive shaft; an oil suction opening and a discharge opening disposed radially and driven by the driven shaft; and a pump device including a variable displacement operation mechanism toward the outside from the axial line.